What is an Engine?
A machine designed to convert any form of energy to mechanical energy to produce work is called an engine, also, devices that burn or consume fuel to carry out mechanical work by exerting a form of force are also known as engines. An engine can also be called a motor, and this term is sometimes used interchangeably in English contexts.
These terms though, have different meanings in engineering. A device that burns or consumes fuel and, in the process, changes its chemical composition to produce mechanical energy is known as an engine, while a device powered by electricity, air or hydraulic pressure to produce mechanical work is known as a motor.
An example of the functioning of an engine is the process through which mechanical energy is obtained from heat. During this process, fuel is burned and turned into heat which is then used to do work, this process is carried out by a heat engine, although this type of process can be done in different ways.
For an entity to be considered as an engine, there has to be the presence of a kind of energy and conversion will have to take place. Mechanical motion is created when an electric engine converts electrical energy, compressed air is used by a pneumatic engine to create mechanical energy. Elastic energy is used by a clockwork engine to get wind-up toys to work.
Devices that convert heat energy into motion can simply be referred to as an engine, automobile gasoline and diesel engines found in trucks, vans and regular vehicles are examples of this type of engine.
Engine in a Vehicle, Truck or Van
Engines are the most essential parts of any wheeled vehicle. Without the presence of the engine, there will be no movement at all, because, for a vehicle to move, mechanical energy must be created which in turn propels the wheel and causes movement of the vehicle. Although the end goal is to get the vehicle to move, the engines by which this process is carried out vary.
The first commercially successful automobile was configured with a lightweight petrol internal combustion engine which operated on the four-stroke Otto cycle. However, the diesel engine which has proven to be more efficient was later created and is commonly used for trucks, buses, and some high end cars.
The use of internal combustion engines for automobiles has been practiced through the years and this is partly attributed to the improvement of the engine control system brought about by the presence of computers placed on board, providing engine management processes as well as electronically regulated fuel injection.
Power output and engine efficiency have been increased by forced air induction through turbocharging and supercharging, the same power characteristics have been given to smaller diesel engines by the application of similar changes. The smaller diesel propelled vehicles we see today are as a result of this.
Diesel engines are known to be 40% more fuel efficient than comparable petrol engines because they produce less hydrocarbon and co2 emissions but higher particulate and NOx
A number of changes have been made starting in the first half of the 20th century in a bid to increase engine power by raising engine capacity. The changes made include raising the pressure in the cylinders to improve efficiency, creating larger engines and speeding up the rate at which the engine produces work. Higher force and pressure were created by these changes which further led to engine vibration and size problems and subsequently stiffer and more compact engines. This, in turn, led to the longer straight line arrangement, replacing v and opposed cylinder layouts.
The large range of engines that are in common use today were produced by the earlier development of automobile engines. During this development, engines have ranged between 1 to 16 cylinder designs, followed by corresponding differences in overall size, engine displacement, weight, and cylinder bores.
Power rating and 4 cylinders Ranging from 19 to 120 hp which is equivalent to 14 to 90 KW were present in the majority of the models which followed. Also, some three cylinders and two-stroke cycles were built, and most engines also had straight cylinders. The smaller engines were commonly located at the rear of the vehicle and air-cooled compression ratio was low.
Types of Engines
Engines are classified based on two criteria the kind of energy they collect in order to create motion and the type of motion they produce.
This is a system that converts heat, thermal energy, and chemical energy into mechanical energy which is used to produce mechanical work. It executes this process by taking a working substance and transforming it from a higher temperature to a lower state temperature.
These are similar to heat engines, but here the heat produced is from a combustion process. Combustion, which is also known as burning, is an exothermic redox chemical reaction between a fuel and an oxidant.
Internal Combustion Engine
In this type of engine, the combustion of the fuel occurs with an oxidizer placed in a combustion chamber. The expansion of high temperature and high-pressure gases which are produced by combustion in an internal combustion engine, apply force directly to the components of the engine such as the turbine blades, piston, and nozzle.
External Combustion Engine
An External combustion engine also known EC engine is a type of heat engine where a combustion process of an external source is used to heat an internal working fluid through the engine heat exchanger. The fluid then acts on the mechanism of the engine to produce motion and usable work. Fluid is released after it has been cooled and compressed. This process is also known as (closed cycle).
Air-breathing Combustion Engine
In this type of combustion engine, the oxygen in atmospheric air is used to burn the fuel rather than using an oxidizer. A continuous stream of air which flows through the air-breathing engine is compressed, mixed with fuel, ignited, and expelled as the exhaust gas. Examples of air-breathing engines include steam engine, gas turbine, reciprocating engine and pulse detonation engine.
Non-Combustion Heat Engines
This type of engines converts heat from non-combustible processes into mechanical energy. For example, a nuclear reaction creates steam and powers a steam engine, fueling the reaction by which hydrogen peroxide is decomposed, and a gas turbine is powered to drive a rocket engine. This is often configured the same way as an internal or external combustion system, but the distinction between them is the different energy source.